U.S. patent application number 13/412876 was filed with the patent office on 2012-09-13 for method for optimizing aircraft landing on a runway.
This patent application is currently assigned to AIRBUS OPERATIONS (S.A.S.). Invention is credited to Anne Dumoulin, Martin Scheuermann.
Application Number | 20120232725 13/412876 |
Document ID | / |
Family ID | 45757340 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120232725 |
Kind Code |
A1 |
Dumoulin; Anne ; et
al. |
September 13, 2012 |
Method For Optimizing Aircraft Landing On A Runway
Abstract
According to the invention, a target vertical speed (Vzo),
defined in relation to the ground, is determined and an optimized
ground slope (.gamma..sub.o), associated with an approach path (A)
to keep track during the landing, is determined on the basis of
said determined target vertical speed (Vzo) and of at least one
outside parameter, said optimized ground slope) (.gamma..sub.o)
being at least equal to a predetermined ground slope
(.gamma..sub.i).
Inventors: |
Dumoulin; Anne; (Toulouse,
FR) ; Scheuermann; Martin; (Merville, FR) |
Assignee: |
AIRBUS OPERATIONS (S.A.S.)
Toulouse Cedex
FR
AIRBUS (S.A.S.)
Blagnac Cedex
FR
|
Family ID: |
45757340 |
Appl. No.: |
13/412876 |
Filed: |
March 6, 2012 |
Current U.S.
Class: |
701/18 |
Current CPC
Class: |
Y02T 50/84 20130101;
Y02T 50/80 20130101; G05D 1/0676 20130101; G08G 5/025 20130101 |
Class at
Publication: |
701/18 |
International
Class: |
G05D 1/10 20060101
G05D001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2011 |
FR |
1151865 |
Claims
1. A method for optimizing the landing of an aircraft (AC) on a
runway (2), said landing comprising an approach phase, defined by
an approach path (A) to be tracked with which there is associated a
predefined ground slope (.gamma..sub.i), and a flaring phase (4),
wherein: in a preliminary step: a target vertical speed (Vzo) in
relation to the ground (Vzo) to be applied to said aircraft upon
the initiation of the flaring phase (4) is defined on the basis of
performances and characteristics being specific to said aircraft
(AC); and as a function of said target vertical speed (Vzo) and of
at least one outside parameter, an optimized ground slope
(.gamma..sub.o), associated with the approach path (A), is
determined, which is higher than or equal to the predetermined
ground slope, and upon the interception by the aircraft (AC) of the
approach path (A), said aircraft (AC) is guided so as to track the
determined optimized ground slope (.gamma..sub.o), associated with
said approach path (A), and to reach the preliminarily defined
target vertical speed (Vzo) upon the initiation of the flaring
phase (4).
2. The method according to claim 1, wherein said outside parameter
belongs to the group of parameters comprising: the calibrated
airspeed (CAS) of the aircraft (AC) with respect to the air; the
outside temperature (To) at a standard height (ho); the horizontal
speed of the wind (Vw); the inclination of the runway (2) with
respect to the horizontal; and the altitude (Zp) of the runway
(2).
3. The method according to claim 1, wherein the optimized ground
slope (.gamma..sub.o) is determined from the target vertical speed
(Vzo), the calibrated airspeed (CAS), the horizontal speed of the
wind (Vw), the outside temperature (To) at the standard height
(ho), as well as from the inclination (.gamma..sub.P) and from the
altitude (Zp) of the runway (2).
4. The method according to claim 1, wherein the horizontal speed of
the wind (Vw), taken into consideration during the determination of
the optimized ground slope (.gamma..sub.o), belongs to a determined
range of values.
5. The method according to claim 3, wherein, for determining the
optimized ground slope, the following steps are carried out: the
density of the air (.rho..sub.c) at the standard height (ho) is
determined from the outside temperature (To) and from the altitude
(Zp) of the runway; the true speed (TAS) of the aircraft with
respect to the air is determined from the speed (CAS) and from the
determined density of the air (.rho..sub.c); and the optimized
ground slope (.gamma..sub.o) is determined from the target vertical
speed (Vzo), from the determined true speed (TAS), from the
horizontal speed of the wind (Vw) and from the inclination
(.gamma..sub.P) of the runway.
6. The method according to claim 1, wherein the determination of
the optimized ground slope (.gamma..sub.o) is obtained thru
geometric construction of a speed triangle.
7. The method according to claim 1, wherein the target vertical
speed (Vzo) is preliminarily defined for each type of aircraft.
8. The method according to claim 1, wherein the optimized ground
slope (.gamma..sub.o) ranges between a predefined lower extreme
value and a predefined higher extreme value, preferably equal
respectively to -3.degree. and to -4.49.degree..
9. A device for optimizing the landing of an aircraft (AC) on a
runway (2), said landing comprising an approach phase, defined by
an approach path (A) to be tracked with which there is associated a
predefined ground slope (.gamma..sub.i), and a flaring phase (4),
wherein it comprises: means (6) for determining, as a function of
at least one outside parameter and a target vertical speed (Vzo)
preliminarily defined from performances and from characteristics
being specific to said aircraft (AC), an optimized ground slope
(.gamma..sub.o) associated with the approach path (A) to be tracked
being higher than or equal to the predefined ground slope
(.gamma..sub.i); and means (7) for guiding the aircraft (AC) upon
the interception of the approach path (A) by the latter, so that it
tracks the determined optimized ground slope (.gamma..sub.o),
associated with to said approach path (A), and it reaches the
preliminarily defined target vertical speed (Vzo) upon the
initiation of the flaring phase (4).
10. The device according to claim 9, wherein, the optimized ground
slope (.gamma..sub.o) being determined from said target vertical
speed (Vzo), the calibrated airspeed (CAS), the horizontal speed of
the wind (Vw), the outside temperature (To) at the standard height
(ho), as well as from the inclination (.gamma..sub.P) and from the
altitude (Zp) of the runway (2), said determination means (6)
further comprise: means (8) for calculating the density of the air
(.rho..sub.c) at the standard height (ho) as a function of the
outside temperature (To) and of the altitude of the runway (Zp);
means (9) for calculating the true speed (TAS) of the aircraft with
respect to the air from the speed (CAS) and the determined air
density (.rho..sub.c); and means (10) for calculating the optimized
ground slope (.gamma..sub.c) from the target vertical speed (Vzo),
from the determined true speed (TAS), from the horizontal speed of
the wind (Vw) and from the inclination (.gamma..sub.P) of the
runway.
11. An aircraft, wherein it comprises a device (5) such as
specified in claim 9.
Description
[0001] The present invention relates to a method for optimizing the
landing of an aircraft on a runway, as well as a corresponding
optimization device.
[0002] As known, according to standard procedure rules, an aircraft
(for instance a civil transport airplane) switches from a descent
start altitude to a final approach start altitude: [0003] either
while carrying out a descent at a constant speed, followed by a
defined approach level, for instance, by an altitude of 3,000 feet
(that is about 914 meters), for decelerating and then stabilizing
at a predetermined intermediary speed, the aircraft maintaining
this level, with this intermediary speed, until it intercepts a
predefined final approach path; [0004] while carrying out a
continuous descent approach, wherein the deceleration level at a
constant altitude is omitted, so that the aircraft descends and
decelerates simultaneously, this step being optimally divided into
several sections each having specific descent slopes.
[0005] Intercepting the approach level, or the last segment of the
approach in a continuous descent, and the approach path defines the
initiation of the final approach phase.
[0006] The standard slope associated with this approach path and
defined in relation to the ground (the reason why it will be
referred to as <<ground slope>> later on) is usually
set at -3.degree.. During the approach phase, the aircraft
decelerates again, keeping track of the approach path, while
spreading the slats, the flaps and the landing gears, so as to
exhibit a landing configuration. At approximately 1000 feet (that
is about 305 meters), the aircraft keeps a stabilized approach at a
predefined approach speed (being, more specifically, a function of
the configuration of the aircraft and of the meteorological
conditions) up to 50 feet (that is about 15 meters), and then
initiates its flare so as to join the runway and complete the
landing.
[0007] It is known as well that, in order to avoid obstacles (for
instance formed by the relief, buildings, etc.), an increased
ground slope approach phase (that is for instance, switching from a
-3.degree. standard ground slope to a -4.degree. ground slope)
could be carried out. It should be noticed that, whatever the final
ground slope to track, the latter is published in the operational
approach procedures as defined by the air authorities.
[0008] It is also known that, in addition to air safety
considerations, an increased ground slope approach phase enables to
reduce the environmental impacts in the vicinity of airports
(including noise and polluting emissions), as, thru the geometric
structure, the aircraft flies higher for a same distance to the
threshold of the runway and that the motor speed necessary to
maintain this slope is lower in general. This explains why the
different actors of the aeronautic field (aircraft manufacturers,
airports, air companies) are eager to develop increased ground
slope approaches.
[0009] Furthermore, it is known that transport civil dedicated
aircrafts generally carry out their final approach on a ground
slope set at -3.degree., while being certified for flying up to
-4.49.degree. ground slopes. Beyond this slope value, the approach
phase is considered, by the international rules, as an approach on
a steep slope and the aircraft should suit additional certification
requirements.
[0010] Although such increased ground slopes (that is higher than
-3.degree. but lower than -4.5.degree.) are regularly followed on
numerous international airports, in order to avoid obstacles, it is
not usual for the aircraft to land abruptly (this is referred to,
in such a case, as a <<hard>> landing), being able to
compromise the good behaviour of the aircraft, including when such
hard landings are daily occurring.
[0011] In other words, in order to stand up to regular increased
ground slope approaches (equal for instance to -4.degree.), it is
indispensable to review the design criteria of the aircraft in
terms of performance, maneuverability, or even of structure, so as
to ensure a secured landing, whatever the characteristics of the
aircraft, the meteorological conditions and the geographical
situations in the vicinity of airports.
[0012] Indeed, increasing the ground slope during a final approach
results, on the one hand, in an increase of the vertical speed of
the aircraft in relation to the ground (also referred to as
<<ground vertical speed>> subsequently) and, on the
other hand, in a decrease of the deceleration abilities of the
aircraft (at the origin of hard landings). It can, for instance, be
shown that, in the case of a conventional speed Vgs, a -1.degree.
increase of a ground slope initially at -3.degree. (that is an
increased ground slope equal to) -4.degree. could result in the
vertical speed Vz increasing by more than 30%.
[0013] An increase of the ground slope (and thus of the vertical
ground speed) involves a review of maneuverability and deceleration
abilities, even redimensioning landing gears, resulting in an
additional embedded load, important modifications of the systems of
the aircraft, as well as the need of an adapted training of
pilots.
[0014] The present invention aims at solving these drawbacks.
[0015] To this end, according to this invention, the method for
optimizing the landing of an aircraft on a runway, said landing
comprising an approach phase, defined by an approach path to be
tracked with which a predefined ground slope is associated, and a
flaring phase, is remarkable in that: [0016] in a preliminary step:
[0017] a target vertical speed in relation to the ground to be
applied to said aircraft upon the initiation of the flaring phase
is defined on the basis of performances and characteristics
specific to said aircraft; and [0018] as a function of said target
vertical speed and of at least one outside parameter, an optimized
ground slope, associated with the approach path, is determined
which is higher than or equal to the predetermined ground slope,
and [0019] as soon as the approach path is intercepted by the
aircraft, said aircraft is guided so as to track the determined
optimized ground slope, associated with said approach path, and to
reach the previously defined target vertical speed at the
initiation of the flaring phase.
[0020] Thus, thanks to this invention, the ground slope of the
approach path is optimized, during the approach phase, while
determining an optimized ground slope (with respect to the ground
slope issued from standard procedure rules) from a target vertical
speed predefined, based on characteristics being specific to the
aircraft and one or more outside parameters, such as those
associated with meteorological conditions, environmental conditions
and characteristics specific to the aircraft.
[0021] Indeed, it has been shown that the flare carried out upon a
landing of an aircraft depends nearly exclusively on the ground
vertical speed of the aircraft, so that is forms an efficient
parameter for characterizing the flare and provides an indication
on the ability of the aircraft to ensure a secured landing and to
avoid an inappropriately throttling up. The present invention is
advantageously based on the fact that the above mentioned outside
parameters disturb the deceleration abilities of the aircraft, at a
set ground slope, and increase the risk that the aircraft should
abruptly land on the runway, so that taking the latter into
consideration in the calculation of the optimized ground slope
enables to reduce the risk of hard landings.
[0022] In other words, setting the ground vertical speed of the
aircraft upon the initiation of the flare (at about 50 feet) to a
preliminarily defined nominal target value, the present invention
will secure the final approach phase, providing a more constant,
repeated and easier flare, while increasing the slope, making
advantageously use of the conditions of the approach being
considered for improving the environmental aspects, without
imposing new designing constraints.
[0023] The higher the ground slope of the approach, the lower the
motor speed of the aircraft along the approach path, reducing the
atmospheric and sound pollution, as well as the fuel consumption of
the aircraft.
[0024] In addition, the optimizing method of the present invention
also has the advantage of being able to be implemented: [0025]
readily in any aircraft; [0026] without any structural modification
of the aircraft; [0027] without modification of the piloting laws
or of the aerodynamic configuration of the aircraft; [0028] without
modification of operational procedures; [0029] without impact on
the air traffic control; [0030] without modification of the airport
facilities on the ground; and [0031] without additional
certification specific to this concept.
[0032] Preferably, the outside parameter(s) belong to the group of
parameters comprising: [0033] the calibrated airspeed CAS of the
aircraft with respect to the air. This speed CAS is a function of
the bulk of the aircraft and of the flight configuration of the
aircraft associated with the approach phase, so that, involving the
speed CAS in the determination of the optimized slope, these last
two parameters (bulk M, flight configuration) are taken into
consideration; [0034] the outside temperature at a standard height;
[0035] the horizontal speed of the wind; [0036] the inclination of
the runway with respect to the horizontal; and [0037] the altitude
of the runway. [0038] Preferably, the optimized ground slope is
determined from the target vertical speed, the calibrated airspeed
CAS, the horizontal speed of the wind, the outside temperature at a
standard height, as well as from the inclination and the altitude
of the runway.
[0039] In addition, the horizontal speed of the wind, taken into
consideration during the determination of the optimized ground
slope, belongs to a determined range of values able to be obtained
from several technological solutions.
[0040] Furthermore, for determining the optimized ground slope
preferably the following steps are carried out: [0041] the density
of the air at the standard height is determined from the outside
temperature and from the altitude of the runway; [0042] the true
speed TAS of the aircraft with respect to the air is determined
from the speed CAS and from the determined density of the air;
[0043] the optimized ground slope is determined from the target
vertical speed, from the determined true speed TAS, from the
horizontal speed of the wind and from the inclination of the
runway.
[0044] In a particular embodiment, the determination of the
optimized ground slope is obtained thru geometric construction of a
speed triangle.
[0045] Moreover, the target vertical speed could be defined
preliminarily for each type of aircraft.
[0046] So as not to decrease the safety margins imposed by the air
safety authorities, the optimized ground slope ranges between a
predefined lower extreme value and a predefined higher extreme
value, preferably equal respectively to -3.degree. and to
-4.49.degree..
[0047] Furthermore, the horizontal speed of the wind could be
obtained according to at least one of the following ways: [0048]
thru measurement of the wind at the level of the control tower of
the runway being considered, without taking gusts into
consideration; [0049] thru retrieving data measured directly by one
or more other aircrafts located in the vicinity of the runway.
[0050] The present invention further relates to a device for
optimizing the landing of an aircraft on a runway, said landing
comprising an approach phase, defined by an approach path to be
tracked with which a predefined ground slope is associated, and a
flaring phase. According to this invention, such a device
comprises: [0051] means for determining, as a function of at least
one outside parameter and of a target vertical speed, preliminarily
defined from performances and characteristics being specific to
said aircraft, an optimized ground slope associated with the
approach path to be tracked being higher than or equal to the
predefined ground slope; and [0052] means for guiding the aircraft
as soon as the latter intercepts the approach path, so that it can
track the determined optimized ground slope associated with said
approach path, and it reaches the preliminarily defined target
vertical speed during the initiation of the flaring phase.
[0053] Moreover, as the optimized ground slope is determined from
said target vertical speed, the calibrated airspeed CAS, the
horizontal speed of the wind, the outside temperature at a standard
height, as well as the inclination and the altitude of the runway,
said determination means preferably comprise: [0054] means for
calculating the density of the air at the standard height as a
function of the outside temperature and of the altitude of the
runway; [0055] means for calculating the true speed TAS of the
aircraft with respect to the air from the speed CAS and from the
determined density of the air; and [0056] means for calculating the
optimized ground slope from the target vertical speed, from the
determined true speed TAS, from the horizontal speed of the wind
and from the inclination of the runway.
[0057] Furthermore, the present invention further relates to an
aircraft comprising a device such as specified hereinabove.
[0058] The FIGS. of the appended drawing will better explain how
this invention can be implemented. In these FIGS., like reference
numerals relate to like components
[0059] FIG. 1 represents a diagram showing the method according to
the present invention.
[0060] FIGS. 2 to 4 each represent a speed triangle allowing for
geometrically determining the optimized slope according to this
invention, in the case of a lack of wind, of a back wind and of a
front wind, respectively.
[0061] FIG. 5 is a block diagram of a device for implementing the
method according to this invention.
[0062] In the situation schematically shown on FIG. 1, an aircraft
AC is in an approach phase, with the aim to land on a runway 2
located at an altitude Zp. After a flight on the altitude approach
level Za or after a continuous descent intermediary approach, the
aircraft AC intercepts a final approach path A, having an optimized
ground slope .gamma..sub.o determined as described subsequently, at
point Pa (corresponding to the intersection of the level Za, or of
the continuous descent approach segment, and of the approach path
A) and descends along said axis A in the direction to the runway 2
so as to decelerate until a stabilized approach speed Vapp at a
stabilization altitude Zs at about 1000 feet(point Ps) for reaching
afterwards the target vertical speed Vzo in relation to the ground
3 being constant at point Po. The latter indicates the start of the
flare 4 following the approach phase.
[0063] As shown on FIG. 1, the optimized ground slope .gamma..sub.o
is higher than the initial ground slope .gamma..sub.i (for instance
.gamma..sub.i=-3.degree. and .gamma..sub.o=-4.degree.) being
determined by standard procedure rules.
[0064] Preferably, the optimized ground slope .gamma..sub.o ranges
between a lower extreme value (for instance equal to -3.degree.)
and a higher extreme value, (for instance equal to -4.49.degree.),
so as not to decrease the safety margins imposed by the air
authorities.
[0065] According to the present invention, in order to optimize the
landing of the aircraft AC on the runway 2, first: [0066] a target
vertical speed Vzo is defined in relation to the ground 3 to be
applied to the aircraft AC upon the initiation of the flare. Such a
vertical ground speed Vzo is defined from performance and
characteristics being specific to the aircraft, for instance thru
simulations carrying out performance and robustness calculations.
The definition of Vzo results from an acceptable compromise between
the safety relating to the flare 4 and the reduction of the (sound
and atmospheric) pollution and of the fuel consumption. In the
remainder, it is considered that Vzo is independent from the
embedded bulk of the aircraft AC, so that Vzo is identical whatever
the embedded bulk. Alternatively, it could be contemplated that Vzo
depends on the bulk embedded on-board the aircraft, so that Vzo
could be determined from embedded bulk/speed Vzo abacuses; and
[0067] the optimized ground slope .gamma..sub.o associated with the
approach path A is determined from the target vertical speed Vzo
and from outside parameters as detailed hereinafter.
[0068] Subsequently, <<outside parameters>> refer to
the parameters associated with the meteorological conditions, the
environmental conditions and the characteristics specific to the
aircraft AC.
[0069] In particular, outside parameters able to be involved in
determining the optimized ground slope according to this invention
include: [0070] the calibrated airspeed CAS of the aircraft AC with
respect to the air; This speed CAS is a function of the bulk M of
the aircraft and the flight configuration of the aircraft AC
associated with the approach phase. Otherwise stated, using the
speed CAS, the bulk M and the flight configuration of the aircraft
AC are indirectly taken into consideration. It should further be
noticed that the higher the bulk of the aircraft AC upon landing,
the higher too the over-all approach speed, resulting in the ground
slope decreasing, associated with the axis A at the vertical iso
speed Vz and conversely; [0071] the outside temperature To at a
standard height ho (for instance equal to 50 feet). The temperature
T of the ambient air act on the tracked ground slope associated
with the axis A to the vertical iso speed. If the temperature T is
lower than the standard temperature To defined at destination, the
tracked ground slope will be finally higher than the initial ground
slope .gamma..sub.i and conversely for higher temperatures; [0072]
the altitude Zp of the runway 2. Indeed, the density of the air
varies as a function of the altitude of the runway Zp, so that the
latter acts directly on the true speed TAS of the aircraft with
respect to the air. Thus, the higher the altitude Zp of the
airport, the lower the density of the air, so that the more the
true speed TAS increases and the tracked ground slope is gentle;
[0073] the inclination .gamma..sub.P of the runway 2 when it is
available in the navigation base. The optimized ground slope
.gamma..sub.o is directly corrected from this inclination
.gamma..sub.P, for instance through geometric construction; and
[0074] the horizontal speed of the wind Vw being one of the most
influent available parameters in the relationship linking the
ground vertical speed of the aircraft and the ground slope
associated with the approach path A. When the ground vertical speed
Vz of the aircraft AC is set, a front wind easily and
instantaneously allows flying along the approach path A with an
increased ground slope at iso air slope. The horizontal speed of
the wind Vw, used for determining the optimized ground slope
according to the method of this invention, could be obtained
according to at least one of the following ways: [0075] thru
measurement of the wind at the level of the control tower of the
runway 2 without taking gusts into consideration; and/or [0076]
thru retrieval of data measured by one or more other aircrafts
located in the surrounding of the track 2 and transmitted directly
to the aircraft AC.
[0077] Several methods for obtaining the horizontal speed of the
wind Vw could be used simultaneously for minimizing error
measurements. Moreover, a determined range of speed values VW could
be defined, to be taken into consideration upon determining the
optimized ground slope .gamma..sub.o. In order to maintain some
safety margin, only part of the wind could be taken into
consideration. For instance, up to 15 kts of front wind, 80% of the
wind could be considered. For stronger winds (the speed Vw of which
is higher than 15 kts), a lower consideration of the wind could be
implemented. Theoretically, the method of this invention enables to
achieve a final approach at iso thrust, iso attitude of the
aircraft AC and iso vertical speed Vz, whatever the horizontal
speed of the wind Vw.
[0078] According to this invention, for determining the optimized
ground slope .gamma..sub.o, the following steps are carried out:
[0079] the density of the air (.rho..sub.c) at the standard height
ho is determined from the outside temperature To and from the
altitude of the runway Zp. More precisely, from the altitude of the
runway Zp, the atmospheric pressure P is deduced at the altitude
Zp, allowing to calculate the density of the air .rho..sub.c at the
standard height ho thru the relationship
[0079] .rho. c = P R To , ##EQU00001##
where R=287.053 J/kg/m.sup.3. [0080] the true speed TAS of the
aircraft is determined with respect to the air from the speed
CAS.
[0081] To this end, the calibrated airspeed CAS is retrieved,
corresponding to the approach speed being considered. This value is
for instance available from the FMS (for Flight Management System).
Afterwards, the true speed TAS is determined thru the
relationship
TAS = .rho. c .rho. o K CAS , ##EQU00002##
where .rho..sub.o=1.225 kg/m.sup.3 and K is a coefficient of
compressibility correction; and [0082] optimized ground slope
(.gamma..sub.o) is determined from the target vertical speed Vzo,
from the determined true speed TAS, from the horizontal speed of
the wind Vw and from the inclination of the runway (.gamma..sub.P).
Such a determination could be obtained in a simplified way thru
geometric construction of a speed triangle. Indeed, as shown on
FIGS. 3 to 5 (on which the inclination of the runway is nil)
presenting respectively the case where there is no wind (Vw=0, FIG.
2), the case where there is some back wind (Vw>0, FIG. 3) and
the case where there is a front wind (Vw<0, FIG. 4), thru
building a speed triangle from the determined speed TAS and the
constant target vertical speed Vzo, the optimized ground slope
.gamma..sub.o is obtained. During the absence of wind (FIG. 2), the
speed of the aircraft AC in relation to the ground Vgs is equal to
the speed TAS (that is TAS=Vgs). In the case of a back wind (FIG.
3), the speed Vgs is higher than the speed TAS (that is TAS<Vgs)
and .gamma..sub.o is less high than that obtained in the absence of
wind. In the case of a front wind (FIG. 4), the speed Vgs is lower
than the speed TAS (that is TAS>Vgs) and .gamma..sub.o is higher
than that obtained in the absence of wind.
[0083] Thus, after determining the optimized ground slope
.gamma..sub.o in the above mentioned way, upon the interception by
the aircraft AC of the approach path A at point Pa, the aircraft AC
is guided so that it tracks the optimized ground slope
.gamma..sub.o associated with the approach path A, and it reaches
the target vertical speed Vzo upon the initiation of the flaring
phase 4 (point Po).
[0084] For determining the optimized ground slope .gamma..sub.o and
guiding the aircraft AC as mentioned hereinabove, the device 5
illustrated on FIG. 5 could be used. It comprises: [0085] means 6
for determining the optimized ground slope .gamma..sub.o,
associated with the approach path A to be tracked, receiving the
outside temperature To at a standard height ho, the inclination
.gamma..sub.P and the altitude Zp of the runway 2, the calibrated
airspeed CAS, the target vertical speed Vzo and the horizontal
speed of the wind Vw; and [0086] means 7 for guiding the aircraft
upon the interception (point Pa) by the latter of the approach path
A, for imposing to it to track the associated optimized slope
.gamma..sub.o and have it reach the target vertical speed Vzo at
point Po.
[0087] The determination means 6 comprise: [0088] means 8 for
calculating the density of the air .rho..sub.c at the standard
height ho as defined hereinabove. They receive the outside
temperature To and the altitude of the runway Zp, via links L1 and
L2. The means 8 are able to deliver, in outlet, the density of the
air .rho..sub.c at the height ho; [0089] means 9 for calculating
the true speed TAS of the aircraft AC as set forth previously. They
receive the density of the air .rho..sub.c as determined by the
means 8 and the calibrated airspeed CAS, via links L3 and L4. The
means 9 are able to deliver, in outlet, the true speed TAS; and
[0090] means 10 for calculating the optimized ground slope
.gamma..sub.o as mentioned hereinabove. They receive the true speed
TAS determined by the means 9, the target vertical speed Vzo, the
horizontal speed of the wind Vw, as well as the inclination of the
runway .gamma..sub.P via links L5, L6, L7 and L9. They are able to
deliver, in outlet, the optimized ground slope .gamma..sub.o so
that it could be processed by the guiding means 7.
[0091] The means 6 for determining the optimized slope
.gamma..sub.o could be integral with the flight management system
FMS or with another embedded system in connection with the flight
management system. Alternatively, they could be outside the
aircraft and have the form of a laptop or be even integrated into a
station on the ground able to communicate the optimized slope
.gamma..sub.o to the aircraft AC. The optimized slope .gamma..sub.o
could be transmitted from the determination means 6 to the FMS, or
even be entered manually in the FMS by pilots.
[0092] Moreover, the guiding means 7 comprise the following means
(not shown on the Figs.): [0093] a calculation means being intended
for determining, usually, piloting instructions from information
received from the determination means 6 via the link L8; [0094] at
least one means for aiding piloting, for example, an automatic
piloting device and/or a flight director, determining, from the
piloting instructions received from said calculation means,
piloting instructions of the aircraft AC; and [0095] means for
actuating controlled organs, such as for instance (direction,
depth) control surfaces of the aircraft, to which the thus
determined piloting instructions are applied.
[0096] Furthermore, it could be contemplated that the determination
of the optimized ground slope .gamma..sub.o and guiding the
aircraft along the axis A with a slope .gamma..sub.o are optional,
providing activation and deactivation functions of such operations
as, for instance, an activation means integrated into the cockpit
of the aircraft AC.
[0097] In addition, it could also be provided that an indication
should be displayed inside the cockpit (for instance) as a visual
signal for notifying the pilots that the method for optimizing the
landing according to this invention is activated. Thereby, pilots
will not be surprised by a later interception of the increased
slope approach path A with respect to that relating to conventional
approaches (ground slope equal to -3.degree.).
* * * * *